This invention relates to fluid dispenser and, in particular, to a dispenser for viscous materials wherein the material is left in a predetermined pattern on an article.
In the manufacture of various electronic devices, it is often desired to form a sealing coating between parts of such devices. One example of such a device is a piezoresistive pressure transducer wherein a silicon die is bonded to a substrate with an elastomeric material, eg. silicone rubber. The elastomeric material acts as an adhesive, a seal, and a stress isolator for the silicon die so that dimensional changes in the die are due to changes in ambient pressure and not dimensional changes in the substrate due to temperature changes.
A problem in the manufacture of such transducers is the need to have the silicone rubber only around the periphery of the die. The central area of the die must be unsupported. For relative pressure transducers, both sides of the chip must communicate to outside of the package. For these devices, the hole through the package must not be plugged by the silicone rubber.
Prior art techniques such as screen printing epoxy for die attach are not suited for small devices, eg. devices having an outside diameter (excluding leads) of 15 mm. Other techniques, such as using a small spatula to spread a thin layer of material or a needle to deposit and join together a series of beads to form the desired shape, are unsuited to mass production and, in particular, to automation.
In view of the foregoing, it is therefore an object of the present invention to provide an improved dispenser for viscous materials.
Another object of the present invention is to provide a dispenser particularly suited to dispensing viscous material in small places.
Another object of the present invention is to provide a dispenser for forming small, open shapes of viscous material on an article.
A further object of the present invention is to provide an improved method for dispensing viscous material.
Another object of the present invention is to provide an improved method for dispensing viscous material in small places.
A further object of the present invention is to provide an improved method for forming small, open shapes of viscous material on an article.